"""防火墙绕过模块"""
import asyncio
import random
import time
from typing import Dict, Any, List
import scapy.all as scapy

class FirewallBypass:
    """防火墙绕过技术"""
    
    def __init__(self):
        self.bypass_techniques = [
            'fragmentation',
            'slow_scan',
            'encoding',
            'source_port_manipulation',
            'ttl_manipulation'
        ]
    
    async def attempt_bypass(self, target: str, port: int, 
                           stealth_mode: bool) -> Dict[str, Any]:
        """尝试使用多种技术绕过防火墙"""
        
        for technique in self.bypass_techniques:
            try:
                result = await self._apply_technique(technique, target, port, stealth_mode)
                if result and result.get('status') == 'open':
                    result['bypass_method'] = technique
                    return result
            except Exception:
                continue
        
        return None
    
    async def _apply_technique(self, technique: str, target: str, 
                             port: int, stealth_mode: bool) -> Dict[str, Any]:
        """应用特定的绕过技术"""
        
        if technique == 'fragmentation':
            return await self._fragmentation_scan(target, port)
        elif technique == 'slow_scan':
            return await self._slow_scan(target, port)
        elif technique == 'encoding':
            return await self._encoding_scan(target, port)
        elif technique == 'source_port_manipulation':
            return await self._source_port_scan(target, port)
        elif technique == 'ttl_manipulation':
            return await self._ttl_manipulation_scan(target, port)
        
        return None
    
    async def _fragmentation_scan(self, target: str, port: int) -> Dict[str, Any]:
        """IP分片绕过"""
        try:
            # 创建分片的SYN包
            ip_layer = scapy.IP(dst=target, flags=1)  # 设置分片标志
            tcp_layer = scapy.TCP(dport=port, flags='S')
            
            # 发送分片包
            packet = ip_layer / tcp_layer
            responses = scapy.sr(packet, timeout=3, verbose=0)
            
            if responses and responses[0]:
                response = responses[0][0][1]
                if response.haslayer(scapy.TCP) and response[scapy.TCP].flags & 0x12:
                    return {
                        'target': target,
                        'port': port,
                        'status': 'open',
                        'method': 'fragmentation_bypass',
                        'response_time': 3
                    }
            
            return {'target': target, 'port': port, 'status': 'closed'}
            
        except Exception:
            return None
    
    async def _slow_scan(self, target: str, port: int) -> Dict[str, Any]:
        """慢速扫描绕过"""
        try:
            # 极慢的扫描速度
            await asyncio.sleep(random.uniform(5, 10))
            
            # 发送单个SYN包
            packet = scapy.IP(dst=target) / scapy.TCP(dport=port, flags='S')
            responses = scapy.sr(packet, timeout=5, verbose=0)
            
            if responses and responses[0]:
                response = responses[0][0][1]
                if response.haslayer(scapy.TCP) and response[scapy.TCP].flags & 0x12:
                    return {
                        'target': target,
                        'port': port,
                        'status': 'open',
                        'method': 'slow_scan_bypass',
                        'response_time': 5
                    }
            
            return {'target': target, 'port': port, 'status': 'closed'}
            
        except Exception:
            return None
    
    async def _encoding_scan(self, target: str, port: int) -> Dict[str, Any]:
        """编码绕过（改变TCP选项）"""
        try:
            # 使用非标准的TCP选项
            tcp_opts = [('MSS', 1460), ('SAckOK', ''), ('Timestamp', (0, 0))]
            
            packet = scapy.IP(dst=target) / scapy.TCP(
                dport=port, 
                flags='S',
                options=tcp_opts
            )
            
            responses = scapy.sr(packet, timeout=3, verbose=0)
            
            if responses and responses[0]:
                response = responses[0][0][1]
                if response.haslayer(scapy.TCP) and response[scapy.TCP].flags & 0x12:
                    return {
                        'target': target,
                        'port': port,
                        'status': 'open',
                        'method': 'encoding_bypass',
                        'response_time': 3
                    }
            
            return {'target': target, 'port': port, 'status': 'closed'}
            
        except Exception:
            return None
    
    async def _source_port_scan(self, target: str, port: int) -> Dict[str, Any]:
        """源端口欺骗绕过"""
        try:
            # 使用常见的源端口（如53, 80, 443）
            common_ports = [53, 80, 443, 20, 21]
            src_port = random.choice(common_ports)
            
            packet = scapy.IP(dst=target) / scapy.TCP(
                sport=src_port,
                dport=port,
                flags='S'
            )
            
            responses = scapy.sr(packet, timeout=3, verbose=0)
            
            if responses and responses[0]:
                response = responses[0][0][1]
                if response.haslayer(scapy.TCP) and response[scapy.TCP].flags & 0x12:
                    return {
                        'target': target,
                        'port': port,
                        'status': 'open',
                        'method': 'source_port_bypass',
                        'response_time': 3
                    }
            
            return {'target': target, 'port': port, 'status': 'closed'}
            
        except Exception:
            return None
    
    async def _ttl_manipulation_scan(self, target: str, port: int) -> Dict[str, Any]:
        """TTL操作绕过"""
        try:
            # 使用不同的TTL值
            for ttl in [64, 128, 255, 32]:
                packet = scapy.IP(dst=target, ttl=ttl) / scapy.TCP(dport=port, flags='S')
                responses = scapy.sr(packet, timeout=2, verbose=0)
                
                if responses and responses[0]:
                    response = responses[0][0][1]
                    if response.haslayer(scapy.TCP) and response[scapy.TCP].flags & 0x12:
                        return {
                            'target': target,
                            'port': port,
                            'status': 'open',
                            'method': f'ttl_bypass_ttl_{ttl}',
                            'response_time': 2
                        }
            
            return {'target': target, 'port': port, 'status': 'closed'}
            
        except Exception:
            return None
